Ingredient info:Look for smoked haddock, also known as finnan haddie, at better supermarkets and at specialty foods stores and pikeplacefish.com.

preparation

Place haddock fillets in a large wide pot.
Cover with 5 cups cold water. Place pot over
medium-high heat and bring to a simmer.
Reduce heat to medium and simmer until
fish is just cooked, about 5 minutes. Transfer
fish to a plate; let cool. Discard skin and
any scales; flake fish into large pieces.
Set a strainer over a medium bowl; strain
poaching liquid and reserve.

Melt butter in a large heavy pot over
medium-low heat. Add leek and celery and
cook over medium-low heat, stirring often,
until soft and translucent, about 15 minutes.
Stir in dry mustard, then reserved poaching
liquid, potatoes, and thyme sprigs. Increase
heat to medium-high and simmer until
potatoes are tender, about 12 minutes.

With a slotted spoon, remove half of the
cooked potatoes and place in a small bowl.
Finely mash potatoes with a fork; return
to chowder to thicken. Remove chowder
from heat and stir in reserved fish, cream,
and chives. Serve in warmed bowls with
Common Crackers
.